import { type UnixUnit } from "../../unix/validate/isValidUnixUnit.js";
/**
 * Convert an ISO 8601 zoned datetime string to a unix epoch value in milliseconds (default) or seconds.
 *
 * - Uses Temporal.ZonedDateTime.toInstant to convert.
 * - Validates epoch unit ("seconds" | "milliseconds").
 * - Returns null for invalid input.
 *
 * @param value zoned ISO 8601 datetime string
 * @param unit optional: "seconds" | "milliseconds"
 * @returns epoch number or null on invalid
 *
 * @example convertZonedToUnix("2024-02-29T12:34:56.789+00:00[UTC]") // 1709200496789
 * @example convertZonedToUnix("2024-02-29T12:34:56.789+00:00[UTC]", "seconds") // 1709200496
 * @example convertZonedToUnix("invalid") // null
 */
export declare function convertZonedToUnix(value: string, ...unitInput: [unit?: UnixUnit]): number | null;